Ligand displacement from tetrakis(OO′-diethyl phosphorodithioate)-lanthanoid(III) anions by triphenylphosphine oxide. X-ray crystal structure of [La{S2P(OEt)2}3(POPh3)2] and [Sm{S2P(OEt)2}2(POPh3)3][S2P(OEt)2]

Abstract

Triphenylphosphine oxide reacts with the anionic complexes [Ln{S₂P(OEt)₂}₄]^–(Ln = La–Lu, excluding Pm and Y) in ethanolic solution to displace one (La–Pr) or two (Nd–Lu and Y) ligands and form the neutral complexes [Ln{S₂P(OEt)₂}₃(POPh₃)₂] or the cationic complexes [Ln{S₂P(OEt)₂}₂(POPh₃)₂]⁺. The crystal structures of the lanthanum and samarium compounds have been determined.

The lanthanum compound crystallises in space group P2₁/c with a= 19.66(2), b= 12.54(1), c= 24.11 (3)Å, β= 94.16(8)°, and Z= 4, and the samarium compound in space group P2₁, with a= 17.90(2), b= 16.84(1)c= 12.54(2)Å, β= 99.98(10)°, and Z= 2. Both structures were solved by conventional Patterson and Fourier, methods and refined to R 0.09 (La) and 0.08 (Sm).

The neutral lanthanum complex has a square antiprismatic structure. The cationic samarium complex has a pentagonal bipyramidal structure. The nature of the bonding is discussed.